Several prominent comic book television series seem to be on the cusp of cancellation this fall.

According to Deadline, Agents of S.H.I.E.L.D. should be considered to be on the bubble for renewal, and could conceivably end up being cancelled after five seasons on the air. Despite the show's low live ratings, Agents of S.H.I.E.L.D. has strong numbers on DVR and overseas. Either way, this show is the only chance Marvel has of getting a series on ABC in the fall, since Inhumans is to be considered dead after one season.

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The CW has its own series on the bubble, with iZombie looking to go either way following Season 4. The show's ratings are considered to be middle of the pack, but a dedicated fanbase could keep the series afloat. After an early Season 3 renewal, Fox's Lucifer could also be in trouble this time around.

As for The CW's superhero shows, everyone is likely to return for another season, including Arrow, The Flash, Supergirl, and Legends of Tomorrow. A strong debut for Black Lightning has also guaranteed another season for the new show as well. This is particularly surprising considering the network's already packed schedule and the reluctance it has shown in the past to air too many superhero shows at once.